The Cathedral of Saint Peter is the mother church of the Roman Catholic Diocese of Belleville, located in Belleville, Illinois. The cathedral parish of Saint Peter was founded in 1842 at a location east of the present structure, and named after Saint Barnabas the Apostle; it was rededicated to Saint Peter in 1847. By 1863, the congregation recognized the need for a larger structure. It constructed a brick church on the cathedral's present site which it dedicated in 1866.